Method of treating textile materials with liquid ammonia

ABSTRACT

CELLULOSE TEXTILE MATERIALS OF IMPROVED STRENGTH ARE OBTAINED BY TREATMENT WITH LIQUID AMMONIA FOLLOWED BY STRETCHING THE MATERIAL DURING THE AMMONIA REMOVAL STEP.

United States Patent METHOD OF TREATING TEXTILE MATERIALS WITH LIQUID AMMONIA Robert M. Gailey, Paisley, Scotland, assignor to J & P Coats Limited, Glasgow, Scotland No Drawing. Filed Nov. 29, 1967, Ser. No. 686,729 Claims priority, application Great Britain, Dec. 2, 1966, 53,960/66 Int. Cl. D06m 1/02 U.S. Cl. 8-125 7 Claims ABSTRACT OF THE DISCLOSURE Cellulosic textile materials of improved strength are obtained by treatment with liquid ammonia followed by stretching the material during the ammonia removal step.

The subject of this invention is a method of treating textile materials of a cellulosic nature.

One of the best known methods of treating textile materials of a cellulosic nature to increase the strength and improve the lustre is the method known as mercerizing. In this process which usually causes an increase in the strength of the material by a figure of up to a maximum of 20%, the textile materials are normally treated in solutions of certain caustic alkalies, sometimes with application of a slight degree of tension during the process. There are several disadvantages associated with the performance on any process which uses caustic alkalies, for example, immediately after the treatment the fibre must be washed very thoroughly otherwise it becomes detrimentally affected. To avoid the difii'culties associated with the use of caustic alkalies itjhas been proposed to use liquid ammonia to treat textile materials since liquid ammonia does increase the lustre Without detrimentally affecting the material and can be comparatively easily removed from the material. The previous proposal for using liquid ammonia required only that the textile material should be immersed in the liquid ammonia for a few minutes, after which it is taken out of the ammonia and the ammonia removed from it. Although the lustre of the material is enhanced by the treatment the strength of the material is little affected.

Because of the huge quantity of textile material in daily production it is obvious that a great saving would be effected if the tensile strength of textile material could be increased without affecting detrimentally its other qualities as then a thread finer than was previously acceptable could be used in any given situation, or the strength of a lower grade thread could be raised to that of a higher grade untreated thread so that such lower grade could be used in situations in which a higher grade thread would otherwise be necessary. As stated above, methods of increasing the strengths of textile materials are known, but these methods have been attended by manufacturing difiiculties. The problem thus is to provide a method of treating textile material which will increase the strength of the treated material without producing undesirable other effects and which does not use substances which can harm the textile material if they are not applied under the closest supervision and control.

The process to be described possesses these desirable characteristics and provides the material with additional 3,560,140 Patented Feb. 2, 1971 ICC unexpected features such as reduced extensibility which results in less tendency to puckering, and improvement in the lustre. In fact, the increase in tensile strength obtainable has been found to be considerably higher than can be produced by any known process.

A process of treating textile materials of cellulosic nature according to the invention consists in first treating the material with liquid ammonia, then subjecting the material to an ammonia-removing treatment and at the same time subjecting the material to a stretching action causing an elongation in the material of between 10% and 30% as measured against the length of the material immediately following the ammonia treatment.

The ammonia may be pure liquid ammonia.

The ammonia-removing treatment may be a treatment with a hot fluid. The hot fluid may be an aqueous fluid such as water or steam. Alternatively the ammoniaremoving treatment may consist in bringing the material into a hot zone, e.g. that provided by a heating device such as a hot plate or an oven. In another ammoniaremoving treatment the material may be subjected to infra red radiation. As a further alternative the ammoniaremoving treatment may consist of generating heat within the material e.g. by the use of a dielectric heating device or an induction heating device operating at high or radio frequency.

It has been found by experiment that the process according to the invention produces an increase in the tensile strength of the textile material which in the case of sewing thread may be as much as 40% and in some cases considerably higher and also improves the lustre. The increase in tensile strength produced by the process according to the invention is far greater than that produced by any previously known process or treatment. The subjection of the material to the previously unknown large degree of stretch stated during the ammonia-removing treatment is an essential part of the process according to the invention and produces the quite unexpected result of the large increase in tensile strength. Extensibility of the material is also reduced and this is a desirable feature as it reduces the tendency to puckering in any fabrics sewn with thread treated by the process. The degree of extensibility and the percentage increase of strength can be adjusted by altering the stretch applied within the range stated.

What is claimed is:

1. A process of treating cellulosic textile materials comprising contacting the material with liquid ammonia, then removing ammonia from the material and at the same time stretching the material causing an elongation in the material of between 10% and 30% as measured against the length of the material immediately following the ammonia treatment.

2. A process as claimed in claim 1 in which the liquid ammonia is pure liquid ammonia.

3. A process as claimed in claim 1 in which the ammonia-removing treatment is a treatment with a hot fluid.

4. A process as claimed in claim 3 in which the fluid is an aqueous fluid.

5. A process as claimed in claim 1 in which the ammonia-removing treatment consists in bringing the material into a hot zone.

6. A process as claimed in claim 1 in which the ammonia-removing treatment consists in subjecting the material to infra red radiation.

7. A process as claimed in claim 1 in which the ammonia-removing treatment consists in generating heat within the material.

References Cited UNITED 4 OTHER REFERENCES Review of Textile Progress, Purification and Bleaching of Cellulosic Materials by L. Chesner, pp. 346347, 1967.

GEORGE F. LESMES, Primary Examiner J. C. COOPER III, Assistant Examiner US. Cl. X.R.

STATES PATENTS Mahn 820 Miller 2:6020 9 Woodell 8125 Lindberg et a1. 8125 10 8116.2 

